/**
 * @param {string[]} string
 * @return {string}
 */


 function longestCommonPrefix(strs) {
   for( let i = 0; i< strs.length; i++) {
    strs[i] =  strs[i].toLowerCase()
    let j = 0
    while(j < strs[1].length) {
      if(strs[0][j] == strs[1][j] == strs[2][j]){
         console.log(j)
      }else {
        console.log(null);
      }
      j += 1
    }
  }
 } 


 let arr= ['aabbccDDEEFFGGHH', 'aabbccDDqwwqwqwDfaeg','aabbccglklklOioioaUOOOIO']

 longestCommonPrefix(arr)